Automated ventilator with assisted compressions

ABSTRACT

A system for performing simultaneous ventilation and resuscitation of a patient includes an oxygen source, at least one inspiration control valve, a breathing apparatus, at least one expiration control valve, at least one indicator, and at least one timer. The breathing apparatus is configured to form an air seal with at least a portion of the patient&#39;s respiratory tract such that a gas including oxygen can flow from the oxygen source to the lungs. The at least one expiration control valve being configured to selectively actuate an exhalation valve. The at least one indicator for indicating when a rescuer should perform a chest compression. The at least one timer for synchronizing actuation of the at least one inspiration control valve, the at least one expiration control valve, and the indicator, thereby enabling continuous compressions to be provided to the patient while the patient undergoes inspiration and expiration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication 61/748,521, filed Jan. 3, 2013, and of U.S. ProvisionalPatent Application 61/731,828, filed Nov. 30, 2012, which are herebyincorporated by reference in their entireties.

COPYRIGHT

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patentdisclosure, as it appears in the Patent and Trademark Office patentfiles or records, but otherwise reserves all copyright rightswhatsoever.

FIELD OF THE INVENTION

Aspects of the present disclosure relate to ventilators, and moreparticularly, to an automated ventilator with assisted compressions.

BACKGROUND OF THE INVENTION

Sudden cardiac arrest is the leading cause of death in the United Statesand Canada and accounts for one in every six deaths. The Centers forDisease Control and Prevention estimate that approximately 405,000people annually in the United States die from coronary heart disease.About 250,000 of these deaths occur outside of a hospital setting.Achieving high survival rates depends upon a public that is well trainedin Cardiopulmonary Resuscitation (“CPR”) because arrival of emergencymedical services typically takes longer than five minutes, butirreversible brain damage predictably develops after only four minutesof cardiac arrest.

CPR is a procedure performed on a patient undergoing cardiac arrest. CPRincludes compression of the patient's chest by a rescuer (alternatively“resuscitator”) and can be performed with or without ventilating thepatient. The chest compressions are performed to create artificial bloodflow in a patient. The rescuer repeatedly compresses the patient's chestin order to manually pump blood through the patient's heart so thatblood continues to circulate to the patient's vital organs. Thesecompressions should occur at a rate of 100 or more compressions perminute. Providing fewer than 100 compressions per minute decreaseseffectiveness of CPR. A problem arises when the lay public does not knowor does not recall the desired rate of compressions. What is more, evenif the rescuer knows the desired rate, it is difficult to maintain aconsistent compression rate without assistance. Further, CPR withoutventilation is less effective than CPR with ventilation because oxygensaturation falls. This drop in oxygen decreases patient survival afterfour to six minutes of compression-only CPR.

Mouth-To-Mouth Ventilation (“MTMV”) CPR is the current standard fortreating out-of-hospital cardiac arrest. During MTMV CPR, the rescuerperforms chest compressions for a period of time, and then stops thecompressions and attempts to ventilate the patient. During ventilation,the rescuer tilts the patient's head back, lifts the chin, pinches thepatient's nose, creates an air seal between the patient's mouth and therescuer's mouth, and provides two rescue breaths by exhaling into thepatient's mouth. Typically, the ratio is thirty compressions to twobreaths. MTMV CPR has several limitations including: (1) rescuer fear ofdisease transference from the patient; (2) interruption of chestcompressions in order to ventilate the patient; (3) inadequate volumesof gas exhaled by the rescuer into the patient's lungs; and (4)ineffective ventilation due to utilization of the rescuer's expiredgasses which are only about 15% oxygen.

MTMV CPR remains the current standard in airway management utilized bythe lay public; however, the lay public has demonstrated consistentdifficulty and hesitation in performing standard MTMV CPR. Studiesillustrate that MTMV CPR is often performed incorrectly, resulting ininadequate ventilation. For example, missing or poorly performing anyventilation steps results in ineffective ventilation. Because of this,patients have better outcomes when bystanders perform CPR withoutattempting to ventilate the patient. Moreover, ventilation effectivenessis inherently limited by utilizing the rescuer's expired gases becausethe fraction of inspired oxygen (“FiO₂”) is only about 15%. Further,even if the rescuer properly performs each step in MTMV CPR, blood flowin the patient is hindered because the rescuer must interrupt theprocess of chest compressions.

Alternatives to MTMV CPR include CPR using Bag-Valve-Mask ventilation,endotracheal intubation, and Laryngeal Mask Airway ventilation. Thesedevices are not typically available to the lay public when performingCPR and some can even endanger the patient if used incorrectly, e.g., bythe lay public. A bag-valve-mask uses a mask to create the air seal overthe patient's mouth and nose. A bag is then compressed by hand in orderto force atmospheric air, which is 21% oxygen, into the patient's lungs.Pressure-sensitive valves on the bag-valve-mask control the direction ofairflow. Use of the bag-valve-mask still hinders blood flow in thepatient because the rescuer must interrupt chest compressions in orderto ventilate the patient.

Endotracheal intubation involves inserting a tube through the patient'smouth and into the trachea. The patient is ventilated by a bag-valveplaced on the exposed end of the tube or the rescuer exhaling into theexposed end. Endotracheal intubation is an advanced procedure thatinvolves slow insertion times and has been shown to have a failure ratein excess of 30%. Further, use of endotracheal intubation still hindersblood flow in the patient because the rescuer must interrupt chestcompressions in order to ventilate the patient.

Laryngeal Mask Airway (“LMA”) ventilation involves inserting a devicesuch as an I-GEL® suppraglottic airway device with a soft, gel-like,non-inflatable cuff (Intersurgical Ltd., Wokingham, Berkshire, UK) intothe patient's mouth for positive pressure ventilation. The I-GEL®suppraglottic airway device is positioned in the supraglottic airway ofthe patient to deliver air to the patient's lungs. The patient isventilated by a bag-valve placed on the exposed end of the I-GEL®suppraglottic airway device or by the rescuer exhaling into the exposedend. Use of the I-GEL® suppraglottic airway device still hinders bloodflow in the patient because the rescuer must interrupt chestcompressions in order to ventilate the patient.

In the case of out-of-hospital cardiac arrest, the current survival rateis 7.6%. As a result, the AMERICAN HEART ASSOCIATION® (American HeartAssociation, Inc., Dallas, Tex.) (“AHA”) has called for researchregarding alternative methods of CPR. Thus, it would be desirable todevelop a system that overcomes the problems and limitations associatedwith traditional methods of CPR to increase rates of survival forpatients suffering from cardiac arrest.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a system forperforming simultaneous ventilation and resuscitation of a patientincludes an oxygen source, at least one inspiration control valve, abreathing apparatus, at least one expiration control valve, at least oneindicator, and at least one timer. The at least one inspiration controlvalve may be disposed between the oxygen source and the patient. Thebreathing apparatus may be disposed downstream from the inspirationcontrol valve and may be configured to form an air seal with at least aportion of the patient's respiratory tract such that a gas includingoxygen can flow from the oxygen source to the lungs. The at least oneexpiration control valve may be configured to selectively actuate anexhalation valve. The at least one indicator is for indicating when arescuer should perform a chest compression, and the at least oneindicator indicates continuously at a regular timed or periodic interval(e.g., at a frequency of 100 indications per minute) simultaneously withthe actuation of the inspiration and expiration control valves. The atleast one timer is for synchronizing actuation of the at least oneinspiration control valve, the at least one expiration control valve,and the indicator, thereby enabling continuous compressions to beprovided to the patient as guided by the continuous periodic indicationsproduced by the indicator while the patient undergoes inspiration andexpiration.

According to another aspect of the present invention, a kit ofcomponents for assisting in resuscitation of a patient includes anindicator, a timer, and an Automatic External Defibrillator (“AED”). Theindicator is configured to indicate when a rescuer should perform achest compression, and the indicator produces audible or visualindications continuously at a regular timed or periodic interval (suchas at a frequency of 100 times per minute) simultaneously with theoperation of the AED during an attempted revival of a human patient. Thetimer is for actuating the indicator at predetermined intervals.

According to yet another aspect of the present invention, a system forperforming automated ventilation with continuous chest compressions of apatient includes an oxygen source, at least one inspiration controlvalve, a breathing apparatus, an expiration control valve, at least onetimer, and a switch. The at least one inspiration control valve may bedisposed between the oxygen source and the patient. The breathingapparatus may be disposed downstream from the inspiration control valve,the breathing apparatus configured to form a hermetic or substantiallyair-tight seal with at least a portion of the patient's respiratorytract such that a gas including oxygen can flow from the oxygen sourceto the lungs. The expiration control valve may be configured toselectively actuate an exhalation valve. The at least one timer is forsynchronizing the actuation of the at least one inspiration controlvalve and the expiration control valve. The switch is for activating theat least one timer. In response to activating the switch, the at leastone timer is configured to selectively actuate the at least oneinspiration control valve and the expiration control valve according topredetermined settings.

Optionally, an indicator can produce an audible or visual indicationcontinuously at a regular timed or periodic interval simultaneously withthe selective actuation operation of the inspiration and expirationcontrol valves.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a system for automated ventilation and assistedcompression of a patient, according to an aspect of the presentinvention.

FIG. 2A is a schematic view of a system for automated ventilation of apatient during an inspiratory cycle, according to an aspect of thepresent invention.

FIG. 2B is a schematic view of the system of FIG. 1A during anexpiratory cycle, according to an aspect of the present invention.

FIG. 3 is a top view of an I-GEL® suppraglottic airway device.

FIG. 4 is a schematic view of an electrical control system for automatedventilation and assisted compression of a patient.

FIG. 5 is a perspective view of a kit of components including anautomatic external defibrillator and an indicator.

FIG. 6 is a graph depicting optimization of the peak pressure appliedversus inspiratory time for systems varying several parameters.

FIG. 7 is a graph depicting the average compression rate by test subjectusing unassisted compressions and metronome-assisted compressions.

DETAILED DESCRIPTION

During chest compressions, the downward thrust portion of thecompression increases intrathoracic pressure and pushes blood out of theheart. This circulates blood throughout the body. After the thrustportion, the chest decompresses and negative pressure is created in theintrathoracic cavity. This decompression pulls venous blood into theheart so that the subsequent chest compression will continue tocirculate blood. If positive-pressure ventilation occurs during thedecompression phase, the negative pressure in the intrathoracic cavityis diminished. This reduces the amount of venous blood that returns tothe heart and decreases effectiveness of the compressions. Therefore,some aspects disclosed herein are designed to deliver positive-pressureventilation during the downward compression phase and to leave thedecompression phase substantially uninhibited.

Further, aspects of the present disclosure help the lay public performresuscitation by replacing difficult to teach MTMV CPR with systems andmethods that are easy to use and that perform continuous, automaticventilation while allowing the rescuer to concentrate on chestcompressions so that continuous blood flow and delivery of oxygen ismaintained to vital organs.

FIG. 1 illustrates a system for automated ventilation and assistedcompression of a patient according to an aspect of the presentinvention. The system 10 includes a control box 12, a gas source 14, anda breathing apparatus 16. As will be described in more detail withreference to FIGS. 2-4, the control box 12 includes timers, a battery,inspiration and expiration control valves, and indicators. The controlbox 12 synchronizes and controls indicators for chest compressions andflow of gas through system 10. The gas source 14 includes a tank 42 ofcompressed oxygen, a supply regulator 44, and a pressure gauge 46. Thesupply regulator 44 receives gas from the tank 42 and reduces thepressure to provide a substantially constant output pressure to thesystem 10. In one non-limiting example, the supply regulator 44 reducesthe pressure from about 3,000 psi to about 50 psi. The pressure gauge 46is disposed upstream of the supply regulator 44 to indicate the pressureof gas remaining in the tank 42. It is contemplated that a pressuregauge may be disposed downstream from the supply regulator 44 toindicate the pressure received by the system 10. It is furthercontemplated that only a downstream pressure gauge may be used. Thebreathing apparatus 16 includes a relief valve 62, an exhalation valve64, and a connector 66. The breathing apparatus 16 is configured suchthat gas may flow between the relief valve 62, the exhalation valve 64,and the connector 66. The relief valve 62 may be a spring-loaded valvethat actuates when the pressure inside of the breathing apparatus 16reaches a predetermined threshold. The exhalation valve 64 may be aone-way valve that allows air to flow from the breathing apparatus 16 toatmosphere during exhalation. The connector 64 is configured tointerface with a ventilating device such as an LMA or respiratory mask.

Referring now to FIGS. 2A and 2B, a schematic of a system for automatedventilation of a patient is shown. The system includes a gas source 102,two inspiration control valves 104, a breathing apparatus 106, anexpiration control valve 108, and a flow control valve 110. The gassource 102 is connected to the two inspiration control valves 104 andthe expiration control valve 108. The flow control valve 110 is disposedin the flow path between the gas source 102 and the expiration controlvalve 108.

The gas source 102 includes a pressurized oxygen tank 122, a supplyregulator 124, and a pressure gauge 126. The pressurized oxygen tank 122stores substantially pure oxygen under pressure. The pressure of oxygenwithin the oxygen tank 122 drops during use because gas is supplied tothe system but not returned to the tank. In one aspect, a medical-gradecompressed-oxygen cylinder is used such as a LUXFER® model M09B (LuxferMedical, Riverside, Calif.) (“the M09B”) carbon fiber compressed oxygencylinder. Carbon fiber oxygen tanks are generally lighter than standardaluminum or steel medical grade oxygen cylinders. Further, carbon fibercoated cylinders can utilize higher service pressures than standardcylinders including a pressure of about 3,000 psi. The M09B loaded toabout 3,000 psi desirably includes enough oxygen to supply to the systemfor more than one hour of continuous use. These characteristics add tothe portability of the system and make the system more compact.

The supply regulator 124 is disposed downstream of the oxygen tank 122and controls the pressure of gas supplied to the system by thepressurized oxygen tank 122. The pressure after the supply regulator 124is lower than the pressure of the oxygen tank 122 and remainssubstantially constant despite varying pressure in the oxygen tank 122.In one aspect, a portable, Emergency Medical Service grade regulatorsuch as the GENTEC® 286MB-25LY (Gentec Corporation, Shanghai, China) maybe used to lower the tank pressure to, for example, about 50 psi. Thepressure gauge 126 is disposed upstream of the supply regulator 124 andprovides a pressure reading of the oxygen tank 122.

The two inspiration control valves 104 are disposed downstream of thegas source 102. In one aspect, the inspiration control valves 104 arethree-port, two-condition solenoids having an OFF state and an ON state.The inspiration control valves 104 are normally in the OFF state. Whenin the OFF state, the inspiration control valves 104 prevent the flow ofgas from the gas source 102 and vent gas from the breathing apparatus106. When in the ON state, the inspiration control valves 104 areactuated and allow gas to flow from the gas source 102 toward thebreathing apparatus 106. In one aspect, the inspiration control valves104 are CLIPPARD® MINIMATIC® E315F-2W012 (Clippard Instrument Co.,Cincinnati, Ohio) solenoid valves. The CLIPPARD® MINIMATIC® E315F-2W012solenoid valves are generally small and lightweight with a rapidactivation time of approximately 10ms. In one aspect, the inspirationcontrol valves 104 are placed on a double manifold such as the CLIPPARD®MINIMATIC® E315M-02 (Clippard Instrument Co., Cincinnati, Ohio). Twoinspiration control valves 104 are used to increase oxygen supplyflow-rate for inspiration while maintaining a rapid response time and alow peak inspiratory pressure. In one experiment, using a singleinspiratory valve resulted in a peak inspiratory pressure above 26 cmH₂O, but using two inspiratory valves resulted in a peak inspiratorypressure below 26 cm H₂O. As used herein, measurements in cm H₂O arerelative to atmospheric pressure. It is contemplated that more or fewerthan two inspiration control valves 104 may be used. It is furthercontemplated that different types of solenoids can be used.

The breathing apparatus 106 includes a pressure relief valve 162, anI-GEL® suppraglottic airway device 164, and an exhalation valve 166. Thepressure relief valve 162 is located downstream from the inspirationcontrol valves 104 and upstream from the I-GEL® suppraglottic airwaydevice 164. The pressure relief valve 162 is configured to actuate andrelease gas from the system if pressure at the valve increases past apredetermined threshold. This can minimize the risk of lung injury andgastric distention by helping to ensure that peak inspiratory pressuresdo not exceed predetermined limits. For example, delivering a breathwith a pressure of about 50 psi during a single chest compressionresults in high peak inspiratory pressures. If the relief valve 162 isconfigured to actuate at, for example, approximately 23 cm H₂O, thesystem can be safely utilized on patients with a wide variety of lungsizes, body physiques, ages, and the like. In one aspect, the pressurerelief valve 162 is the ALLEGIANCE® 2K8082 (Allegiance Corporation,McGaw Park, Ill.). As will be described more in relation to FIG. 2below, the I-GEL® suppraglottic airway device 164 is configured to beinserted into the mouth of the patient and transfer gas between thelungs of the patient and the system.

The exhalation valve 166 is a one-way valve that allows gas to flow fromthe I-GEL® suppraglottic airway device 164 to the expiration controlvalve 108. The exhalation valve 166 is configured to allow gas expelledfrom the lungs of the patient to escape the system. In one aspect, theexhalation valve 166 is a low-resistance, mushroom-style valve such as a2018 from BIO-MED DEVICES® (Bio-Med Devices, Guilford, Conn.). It iscontemplated that other types of valves may also be used.

The expiration control valve 108 is used to control the operation of theexhalation valve 166. In one aspect, the expiration control valve 108 isa three-port, two-condition solenoid having an OFF state and an ONstate. The expiration control valve 108 is normally in the OFF state.When in the OFF state, the expiration control valve 108 prevents theflow of gas from the gas source 102 and vents gas to depressurize theexhalation valve 166. When in the ON state, the expiration control valve108 is actuated and allows gas to flow from the gas source 102 to theexhalation valve 166. In one aspect, the expiration control valve 108 isa CLIPPARD® MINIMATIC® E315F-2W012 as described above.

The flow control valve 110 is disposed between the supply regulator 124and expiration control valve 108. The flow control valve 110 lowers thepressure that the exhalation valve 166 is exposed to. In one aspect, theflow control valve 110 lowers the pressure to about 26 cm H₂O, theworking pressure of the exhalation valve 166.

Referring now to FIG. 3 an I-GEL® suppraglottic airway device 164 isshown. The I-GEL® suppraglottic airway device 164 includes a connector220, a bite block 222, a gastric vent 224, and a cuff 226. The cuff 226defines an aperture 228 that runs to the connector 220 and is configuredto transfer gasses into and out of the lungs of the patient. Theconnector 220 is configured to interface with a gas supply such as abag-valve. Alternatively, a rescuer may exhale gasses directly into theconnector 220. The bite block 222 is a semi-rigid portion of the I-GEL®suppraglottic airway device 164 that prevents the aperture 228 fromcollapsing if the patient bites down. The cuff 226 forms an air orsubstantially hermetic seal in the patient's supraglottic area such thatgasses passed through the aperture 228 enter the lungs. In some aspects,the air seal is airtight or substantially airtight and inhibits orprevents air from moving into or out of the patient's lung(s) unless ittravels through a predetermined path such as, for example, the aperture228. In other aspects, the air seal is not entirely airtight and allowssome air to pass. Put another way, even though the air seal may not becompletely airtight, the air seal is such that the patient's lung(s) canstill receive adequate oxygenation.

Advantageously, the I-GEL® suppraglottic airway device 164 can beinserted blindly into a patient's mouth. When correctly positioned, theI-GEL® suppraglottic airway device 164 can be used to deliver positivepressure ventilation by using, for example, a bag-valve. Use of theI-GEL® suppraglottic airway device 164 helps prevent transfer of bodyfluids between the rescuer and the patient when compared with MTMV CPR.Further, proper use of the I-GEL® suppraglottic airway device 164 isrelatively easily taught. In fact, the American Heart Association hasadded the use of LMAs such as the I-GEL® suppraglottic airway device 164into both the basic CPR and Advanced Cardiovascular Life Supportprotocols as an alternative to MTMV CPR. What is more, the I-GEL®suppraglottic airway device 164 advantageously secures the airway moreconsistently and quickly than other methods of ventilation discussedabove.

Referring now to FIG. 4, an electrical control system 300 for automatedventilation with assisted compressions of a patient is shown accordingto one aspect. The system includes a battery 302, an assistedcompression mechanism 304, an automated ventilation mechanism 306, and aswitch 308. The switch includes an ON and OFF position. In the OFFposition, no electricity flows through the circuit. In the ON position,the switch 308 allows electricity to flow from the battery 302 to theassisted compression mechanism 304 and the automated ventilationmechanism 306. In one aspect, the battery 302 is a 12-volt, 350milliamp-hour, Lithium Polymer battery that can power the system 300 forover 8.5 hours of continuous use.

The assisted compression mechanism 304 includes a timer 342, an audibleindicator 344, and a visual indicator 346. The audible indicator 344 andthe visual indicator 346 are electrically connected to an output of thetimer 342. The timer 342 is configured to output an electrical signal atpredetermined intervals indicating when the rescuer is supposed to applya chest compression. In one aspect, the timer outputs a square-wavepattern at about 100 beats per minute (1.67 Hz). When the electricalsignal is output, the audible indicator 344 outputs a sound that can beheard by the rescuer. In one aspect, the audible indicator 344 functionslike a metronome by outputting a continuous and regularly repeatingsound (or visual) pattern at a regular frequency (e.g., 100 times perminute or 1.67 Hz) simultaneously with the selective actuation of thecontrol valves 104, 108. This can be accomplished, for example, by usinga buzzer that outputs a noise of about 90 dB in order to signal to therescuer when to apply a chest compression. Also, when the electricalsignal is output, the visual indicator 346 may output a visual signalthat can be seen by the rescuer. In one aspect, the visual indicator 346is a light emitting diode that signals the rescuer to apply a chestcompression. It is also contemplated that only one type of indicator ormore than two types of indicators may be used.

The automated ventilation mechanism 306 includes a timer 362, aninspiration control valve 364 and an expiration control valve 366. Thetimer 362 is configured to output an electrical signal(s) atpredetermined intervals to switch the inspiration control valve 364 andthe expiration control valve 366 from the OFF state to the ON state. Inone aspect, the timer 362 delivers an output signal of about 12 volts ina square wave pattern that causes the control valves 364, 366 to be inthe ON state for about 420 ms and the OFF state for about 3.84 seconds.These times may be selected so that the rescuer performs a single chestcompression during the ON state and another six chest compressionsduring the OFF state.

In some aspects, the timers 342, 362 are operatively connected so as tosynchronize operation of the assisted compression mechanism 304 and theautomated ventilation mechanism 306. It is contemplated that theassisted compression mechanism 304 may be in a system without theautomated ventilation mechanism 306. Alternatively, the automatedventilation mechanism 306 may be in a system without the assistedcompression mechanism 304. Additionally or alternatively, the assistedcompression mechanism 304 and the automated ventilation mechanism 306may share a single timer.

Referring now to FIGS. 2A-2B, an inspiration and expiration cycle of thesystem 100 is described. During inspiration the control valves 104, 108are in the ON position. The expiration control valve 108 appliespositive pressure to the downstream side of the exhalation valve 166 inorder to keep the exhalation valve 166 from operating. The twoinspiration control valves 104 pass gasses from the gas source 102 tothe breathing apparatus 106. During the inspiration cycle, the rescuerapplies chest compressions to the chest of the patient as guided by theaudible or visual indications produced by the indicator 344, 346 at aregular and continuous frequency, such as 100 times per minute. In otherwords, one or both of the indicators 344, 346 produce the audible (e.g.,outputting a brief buzzer sound) or visual (e.g., briefly activating alight-emitting diode) while the control valves 104, 108 are selectivelyactivated to supply gas to the breathing apparatus 106 and allow ventingof expired air from a human patient from the breathing apparatus 106 tothe atmosphere. After a predetermined period of time, control valves104, 108 are switched to the OFF state and the expiration cycle begins.While in the OFF state, neither the inspiration control valves 104 northe expiration control valve 108 transfer gas from the gas supply 102 tothe breathing apparatus 106. Further, while in the OFF state, bothinspiration control valves 104 and the expiration control valve 108 ventair from the breathing apparatus 106 to the atmosphere. The resultingdrop in gas pressure between the expiration control valve 108 and theexhalation valve 166 allows the exhalation valve 166 to operate,allowing for rapid and complete expiration. When no pressure is applied,the lungs of the patient evacuate and force gas through the I-GEL®suppraglottic airway device 164 and into the system. The exhaled gasflows through the exhalation valve 166 and the expiration control valve108 where the exhaled gasses escape to the atmosphere. During theexpiration cycle, the rescuer continues to apply chest compressions asguided by the indications produced by the indicator 344, 346 at aregular and continuous frequency. Because the machine automaticallyswitches between the inspiration cycle and expiration cycle without anyinput from the rescuer, chest compressions may be continuously appliedwithout interruption simultaneously with the operation of the controlvalves 104, 108.

The systems and methods disclosed herein are generally more effectivethan conventional MTMV CPR. What is more, the lay public can generallybe easily taught to insert an LMA and perform both continuous chestcompressions and effective ventilation using aspects of the presentdisclosure, whereas standard MTMV CPR may be difficult to teach.Further, most rescuers in the lay public cannot properly ventilate apatient using MTMV CPR, and, thus, should perform chest-compression-onlyCPR to avoid wasting critical time attempting to deliver ventilationthat is often ineffective. In an example study, one-third ofparticipants were unable to deliver any successful breaths using MTMVCPR despite having been taught how to perform MTMV CPR using standardAHA training techniques by a certified AHA instructor only minutesbefore trials were performed. What is more, the average Minute Volumefor those that could deliver a successful breath was only about 628 mL,which is not enough to justify the average non-compression time of about63.43 seconds needed to perform the MTMV CPR.

Further, aspects of the present invention can be used in a wide varietyof patients and clinical scenarios from pediatrics to adults because ofthe variable nature of the volumes and pressures used in ventilation.Average and larger size adults, with normal lung compliance, willgenerally receive the full tidal volume of about 250 mL because the peakpressure created by ventilation with the system is below the pressurerelief valve setting. Smaller patients will trip the relief valve whenthe desired peak inspiratory pressure is reached, corresponding to theappropriate tidal volume for the size of the patient. Patients withstiff and/or diseased lungs may cause the pressure relief valve to tripbefore the delivery of a full tidal volume, which is viewed as a benefitand not a limitation of the present disclosure because the pressurerelief valve is designed to deliver the maximum tidal volume beforedangerous pulmonary barotrauma or gastric distention is created.

The proliferation of Automatic External Defibrillators (“AED”) in agrowing number of public areas indicates that it is possible tostrategically store technological devices in places that can be utilizedby the lay public in CPR. Systems according to the present disclosurecould similarly be placed in public areas in addition to AEDs. What ismore, aspects of the present invention may be combined with typical AEDsin a single system. The combined device would be much smaller andsimpler than two separate devices because, for example, many of thecomponents of AEDs could be shared with aspects of the presentdisclosure.

One example of such a shared component is the voice assist function ofmany AEDs. This function could be modified to include instructions onLMA insertion and methods associated with the present disclosure inorder to further aid lay responders. Software modifications may also bemade to provide the metronome feature using the voice assist function ofthe AED.

Further, aspects of the present disclosure may be modified to inject CPRmedications into the trachea through the LMA using pneumatics and amodified AED algorithm. The American Heart Association Advanced CardiacLife Support protocol is specific about which medications should beinjected at what time. A software algorithm can follow the AHAguidelines using the electro cardiogram as a driver, which is alreadypart of the AED. The software of an AED may recognize cardiac rhythm anddetermine when life supporting medications should be delivered by thesystem. Gas-pressurized injections of medications, such as epinephrine,can, therefore, be delivered into the trachea by the system via the LMAunder complete control of the AED software. This type of AED algorithmdesign can, for the first time, bring advanced life support techniquesto lay-public CPR.

Yet further, aspects of the present disclosure may be modified toinclude a device that performs automated chest compressions. Automatedchest compression devices simulate manual chest compressions by applyingmechanical force to the chest of the patient. A variety of mechanismsmay be used to accomplish the mechanical chest compressions such aspneumatic vests, load-distributing bands, and actuators includingpneumatic or electric-driven pistons. Some such devices include theAUTOPULSE® (Zoll Medical Corporation, Chelmsford, Mass., USA), theLIFE-STAT® device (formerly the THUMPER®) (Michigan Instruments, GrandRapids, Mich., USA), and the Lund University Cardiac Assist System(LUCAS®) (Jolife AB, Lund, Sweden). Such devices assist in avoidingrescuer fatigue and dwindling compression quality over time. A systemincorporating both automated ventilation and automated compression mayinclude, for example, the ventilation system 100 and a modifiedelectrical control system. The modified electrical control system mayinclude, for example, the battery 302, the automated ventilationmechanism 306, and the switch 308. The timer 362 would be synchronizedwith the compressions from the automated compression device to producethe same ventilation effect as described above.

In some aspects, a system provides a combination of automatedventilation, automatic defibrillations, automated compressions, andautomated application of medications. Such a system could be used on apatient to provide continuous, uninterrupted compressions andventilation to the patient over an extended period of time. Theuninterrupted compressions and ventilation could continue duringtransportation to a hospital. This includes ventilation and chestcompressions occurring while moving the patient from the initiallocation of cardiac arrest to an ambulance, while transporting thepatient in the ambulance, and while moving the patient from theambulance to the hospital. Further, the automatic defibrillation andautomatic application of medications allow for advanced resuscitationtechniques without unnecessary interruptions to the ventilation orcompressions.

Referring now to FIG. 5, a kit of components 500 may be provided thatincludes an AED 502 and an indicator 504 configured to indicate when achest compression should be performed. The indicator may be, forexample, the audible indicator 344 and/or the visual indicator 346. Atimer may be included with the indicator 504. The indicator may beincluded in the AED 502 itself.

Aspects of the present disclosure use pressurized oxygen forventilation. Alternatively, gas containing lower levels of oxygen can beused when pure oxygen is contraindicated or not desired. For example,firefighters have limited ability to use oxygen in the presence of anignition source. Lightweight tanks filled with atmospheric air can beused instead of oxygen. Alternatively, a pump can be used to compressair and supply the system with air as-needed.

Additionally, aspects of the present disclosure can be used to deliverelectrical shock for cardiac defibrillation. For example, one of the twoexternal pads used for cardiac defibrillation by the AED may be replacedby aspects of the present disclosure such as the LMA. The LMA would bemodified to carry a charge to a desired location within the patient. Theinternal placement of the LMA and the preferred contact with an internalmucosal membrane holds promise of dramatically improved electricalcontact and effectiveness, which may result in increased effectivenessof defibrillation or lower power needed.

In some aspects, the system can be modified to monitor chestcompressions in order to determine whether the chest compressions areadequate and/or properly timed. In one nonlimiting example, a sensormonitors air pressure proximate to the respiratory system of thepatient. A chest compression generally increases intrathoracic pressureand, similarly, increases measured air pressure of the respiratorysystem. This rise can be compared to a baseline or calibration curve todetermine the adequacy and/or timing of the compression. In anothernonlimiting example, the system includes a pressure sensor disposedbetween the chest of the patient and the hands of the rescuer. Thepressure sensor can be used to determine, for example, the adequacyand/or timing of the compression. In yet another nonlimiting example,the system may include an accelerometer disposed, for example on a handof the rescuer, to determine the adequacy and/or timing of the chestcompression.

A system with monitored chest compressions can be further modified toinclude a dynamic indicator. For example, the indicator could signalinadequate chest compressions by providing a different audio and/orvisual signal, becoming louder, showing an alternate color, and/or usinga voice command to inform the rescuer to apply more force withcompressions.

Aspects of the present disclosure can be modified to deliver a widevariety of ventilation modes. This includes modification of tidalvolume, pressure relief, and respiratory rate to meet the specific needsof many situations, even when cardiac arrest is not an issue. Forexample, firefighters or Emergency Medical Services can use systems andmethods of the present disclosure for emergency transport duringextraction or in field applications where a lightweight ventilator isimportant.

EXAMPLES

Endpoint variables were measured to compare the lay public'seffectiveness in conventional MTMV CPR and CPR using an Example Systemaccording to the present disclosure, including: (1) volume ofventilation per minute (“Minute Volume”); (2) Minute Volume afteraccounting for dead-space ventilation; (3) total period without chestcompressions; (4) total number of chest compressions; (5) rate of chestcompressions; (6) time to first compression; and (7) time to firstventilation. Further, the lay public's self-reported preferences betweenMTMV CPR and the automated ventilation and assisted compression systemwere recorded.

The example system was designed to administer breaths with aninspiration time (I-Time) as short as the downward chest compressionphase. At about 100 compressions per minute, this inspiration time isapproximately 400 milliseconds. The I-GEL® suppraglottic airway devicehas a maximum recommended peak pressure of approximately 26 cm H₂O.Because of short the I-Time and maximum peak pressure, the examplesystem delivers frequent, low-tidal-volume (V_(t)) breaths.

The Anatomic Dead Space is the total volume of the airway tract leadingfrom the patient's mouth and nose to the alveoli in the lungs. In anadult male, this dead space is approximately 150 mL. The dead spacevolume must be subtracted from the total tidal volume when calculatinghow much air actually reaches the patient's alveoli to participate ingas exchange. When MTMV CPR is performed according to AHA standards, theeffective Minute Volume is approximately 1.4 L plus dead space. Thisvolume includes expired air with a fraction of inspired oxygen of about15%. The example system was designed to administer the AHA standardeffective Minute Volume of about 1.4 L. However, the example systemdelivers a fraction of inspired oxygen of about 100% and, thus, providesapproximately 6.67 times more oxygenation than properly-performed MTMVCPR.

The example system was tested to determine parameters needed to supplythe effective Minute Volume using tidal volumes delivered in less thanabout 400 milliseconds with less than about 26 cm H₂O peak inspiratorypressure. The variables that were manipulated to accomplish thisincluded oxygen supply pressure, number of pneumatic valves, diameter ofventilation circuit, supply valve orifice, inspiratory time, and reliefvalve pressure setting. The goal was to determine settings thatdelivered the largest tidal volume within about 400 milliseconds whilemaintaining peak pressures below about 26 cm H₂O.

FIG. 6 illustrates the results of sixty different trials performed usingdifferent combinations of the above variables with multiple tests beingperformed for each combination of dependent variables. “Vt” indicatesthe tidal volume, and “peep”/“no peep” indicates whether PositiveEnd-Exhalation Pressure (e.g., a relief valve) was used. All of thesystems included two solenoid valves unless indicated to include “3valves.” For example, the hollow squares labeled “Vt 350 no peep”indicate that the tidal volume was 350 mL, that no pressure relief valvewas used, and that two solenoid valves were used (one inspiration, oneexpiration). The solid squares labeled “Vt 250 no peep and 3 valves”indicate that the tidal volume was 250 mL, that no pressure relief valvewas used, and that three solenoid valves were used (two inspiration, oneexpiration). The supply pressures tested ranged from about 40 psi toabout 110 psi. Measurements of ventilation volume, flow, pressure,inspiratory time, and expiratory time were taken with a MALLINCKRODTPURITAN BENNET BREATHLAB PTS-2000 VENTILATOR ANALYZER™ (MallinckrodtGroup, Hazelwood, Mo.).

As shown in FIG. 6, the Example System including threesolenoid-controlled pneumatic valves (two for inspiration, one forexpiration), a spring-controlled pressure relief valve set to about 20cm H₂O, and a tidal volume of about 250 mL delivered in about 420 msproduces peak inspiratory pressures of approximately 23 cm H₂O. Assuminga normal adult dead-space volume of about 150 mL, the effectiveventilation will be about 100 mL per breath. Thus, an effective minuteventilation of about 1.4 L required a respiratory rate of about 14breaths per minute.

Once the number of breaths per minute was determined, the ventilationand chest compressions were synchronized. The built-in metronome featurewas designed to sound at about 100 beats per minute. The inspiratoryphase was synchronized with the metronome feature to deliverpositive-pressure breaths during the downward chest compression phase.This generally increased intrathoracic pressure during the chestcompression and enhanced the effectiveness of chest compressions. Also,this synchronization minimized the negative effect of ventilation onvenous return to the heart during the decompression phase of chestcompressions. Using this information, the Example System was set todeliver one breath for every seven chest compressions. This rateprovided the required fourteen breaths in slightly less than one minute.

An additional benefit of the Example System is that it is lightweight,compact, and portable. The main module used in the present examplemeasured about 4 inches (10.16 cm) by about 2 inches (5.08 cm) by about6 inches (15.24 cm) and it weighed only about 28.6 ounces (810.8 g).This was the smallest and most lightweight ventilator at the time it wasbuilt. This lightweight and compact design makes the Example Systemideal for transport, storage, and use by rescuers. Further, the exampleventilator was the only ventilator that functions with a simple on/offswitch. This makes the system incredibly easy to use, especially for thelay public.

The Example System was tested using 44 participants from the lay public,including 18 men and 26 women. The education levels of the sample groupare detailed in Table 1.

TABLE 1 Education Achieved Education Achieved Frequency PercentCumulative Percent Currently in High School 11 25.0 25.0 Completed HighSchool 5 11.4 36.4 2-Year College 3 6.8 43.2 4-Year College 16 36.3 79.5Graduate School 9 20.5 100.0 Total 44 100.00 100.0

The age range of the subjects was 14-60 (mean 37+/−15.0). Persons bothcertified in CPR (n=12) and not certified in CPR (n=32) were acceptedinto the study. Subjects were screened for physical capabilities per theAHA guidelines before their participation in the study. The screeningprocess informed subjects of the physical exertion required during CPRand asked them to disclose any information that may hinder their abilityto participate. No subjects were eliminated.

Measurements were taken using a LAERDAL® SIMMAN® (Laerdal Medical,Stavanger, Norway) manikin patient simulator. The pulmonary system ofthe manikin was upgraded using a MAQUET® 190 (Maquet Medical Systems,Wayne, N.J.) Adult Test Lung to simulate human lung compliance of about20 cm H₂O and allow for accurate tidal volume measurements.Additionally, the manikin was modified to include a MALLINCKRODT PURITANBENNET BREATHLAB PTS-2000 VENTILATOR ANALYZER™ (Mallinckrodt Group,Hazelwood, Mo.), which continuously measured tidal volumes and pulmonarypressure. To capture all other variables, subjects were videotapedallowing for later analysis of time to first ventilation, time to firstcompression, total time of no compressions, total number ofcompressions, and compression rate.

Subjects were taught MTMV CPR and automated ventilation and assistedcompression CPR using instruction and practice videos. In both teachingscenarios, subjects had the ability to ask the instructor any questionspertaining to their CPR attempts. A placebo ventilator was also utilizedthat was similar to the Example System, but applied a differentventilation pattern and lacked a metronome feature. The placebo teachingand trial phase was always performed after use of the Example System toavoid skewing the Example System's results through prior practice withthe I-GEL® suppraglottic airway device.

Time began when the subject first touched the manikin or the airwaydevice. Subjects were asked to perform CPR for 3 minutes for each of thethree methods tested. The tidal volume of each breath was recorded inorder to calculate the average Minute Volume and average non-dead spaceMinute Volume for all three minutes. The time to first ventilation wasthe time until the first breath greater than about 150 mL was delivered.The rate of chest compressions was calculated by dividing the totalnumber of compressions in three minutes by the total time used toperform chest compressions.

The subjects also completed a survey to assess participant preferencesafter all trials were performed. These preferences included satisfactionwith each technique, difficulty using each technique, likelihood ofperforming each technique, preference ranking, protection from bodyfluids, and importance of the metronome feature.

The primary endpoint variables and the post-survey preference resultswere compared using the Wilcoxon Signed Ranks test, a nonparametriccounterpart to the paired t-test. Alpha was set at 0.01, instead of theusual 0.05, because several analyses were performed. This“Bonferroni-type” adjustment was applied because it is more likely tofind a significant difference at the nominal 5% level when one does notactually exist with this number of statistical tests. In order todetermine the variation in compression rates between the groups, thecoefficient of variation (CV) was computed for both methods.

The endpoint variables are described in Table 2 below.

TABLE 2 Endpoint Variables Variable MTMV CPR Example System P-ValueMinute Ventilation (L) 0.628 ± 0.684 4.064 ± 0.620 P < 0.001 Non DeadSpace Minute 0.314 ± 0.516 2.126 ± 0.533 P < 0.001 Ventilation (L) Timeto first ventilation 94.11 ± 75.93 6.70 ± 2.47 P < 0.001 (seconds) Totalnumber of compressions 200 ± 19  286 ± 7  P < 0.001 Time to firstcompression 0.00 ± 0.00 8.95 ± 3.10 P < 0.001 (seconds) Total time of noChest 63.43 ± 7.39  8.82 ± 2.79 P < 0.001 Compression (seconds)

As shown, all measured endpoint variables were statisticallysignificant. Subjects were able to provide significantly more totalMinute Volume and non-dead space Minute Volume using the Example Systemthan with MTMV CPR (p<0.001). The average Minute Volume for MTMV CPR wasonly about 628 mL compared to more than about 4000 mL with the ExampleSystem. Surprisingly, seventeen participants were completely unable toprovide any successful breaths using MTMV CPR while the Example Systemprovided successful ventilation during all trials.

What is more, subjects were able to limit the total time of no chestcompressions to an average of about 8.8 seconds when using the ExampleSystem rather than the about 63.4 seconds with MTMV CPR (p<0.001). Whenusing the Example System, subjects were able to provide an average ofabout 286 chest compressions during the three minute trials compared toonly about 200 chest compressions with MTMV CPR (p<0.001). This is anincrease of about 43%.

Because so many participants were unable to provide successful breathsusing MTMV CPR, the average time to first ventilation was about 94.11seconds with MTMV CPR compared to only about 6.70 seconds with theExample System (p<0.001).

Referring now to FIG. 7, a graph depicting the average compression rateby test subject using unassisted MTMV CPR and using the Example Systemis shown. Both average rates were within the AHA guidelines of 100 chestcompressions per minute; however, the average standard deviation forMTMV CPR is about 13.01 compressions per minute, while the standarddeviation for the metronome-assisted compressions is only about 2.00compressions per minute. Notably, during MTMV CPR, sixteen participantsperformed compressions at a rate significantly below the AHA recommendedstandard. The slowest rate was equal to about 72.6 chest compressionsper minute. In contrast, no one using the Example System performed chestcompressions at a rate significantly below the AHA standard. Further,the coefficient of variation was about 12.7% with MTMV CPR versus onlyabout 2% with the Example System. Thus, use of the metronome featureprovided greater consistency around the desired rate than MTMV CPR(p<0.001).

The time to first chest compression was shorter (p<0.001) with MTMV CPRthan with the Example System. This is because MTMV CPR always beginswith chest compressions. However, the average time to first chestcompression was only about 8.95 seconds with the Example System. Thisdifference is not significant and is far outweighed by the otherbenefits provided by the Example System.

Further, as shown in Tables 3A and 3B below, the self-reported surveyresults show that Example System was preferred to MTMV CPR in all fivecategories (p<0.001). The categories included satisfaction, ease of use,likelihood to use, rank, and protection from body fluids. The subjectsrated satisfaction, ease of use, and likelihood to use on a scale from 1to 5, 1 being the best (e.g., 1-very satisfied with the airway techniqueand 5-very dissatisfied with airway technique). The subjects rated theorder of preference from 1-3, 1 being the best. The subjects were alsoasked to rate the helpfulness of the metronome feature. About 95.5% ofsubjects rated the metronome feature helpful to very helpful. The otherabout 4.55% were indifferent. No one reported that the metronome featurewas detrimental to adequate chest-compression timing. Numbers on thetables below represent the average rating given (1-5 for satisfaction,ease of use, likelihood of use; 1-3 for order of preference) andpercentages are based on the number of participants selecting a givenoption.

TABLE 3A Preferences and Perceptions MTMV Example System Placebo CPR CPRCPR P-Value Satisfaction 2.59 1.40 2.01 P < 0.001 Ease of use 2.69 1.312.00 P < 0.001 Likely to use 2.73 1.45 1.82 P < 0.001 Order ofpreference 2.75 1.31 1.94 P < 0.001 Protection from body 0.0% 100%believed the Example P < 0.001 fluids System or Placebo provided betterprotection

TABLE 3B Preferences and Perceptions MTMV Example Placebo CPR Systemsystem Satisfied or very satisfied 31.8%   100% 68.2% Easy or very easyto use 18.2%  93.2% 59.1% Very probably or definitely 31.8%  95.5% 70.5%likely to use Ranked first as preferred  6.8%  70.5% 22.7% technique inactual CPR Most likely to protect from body  0.0% 100% believed eitherthe fluids Example System or Placebo provided better protectionMetronome is helpful or very  95.5% helpful

Subjects in this study were able to deliver over six times more MinuteVolumes, over seven times more non-dead space ventilation, 44% morechest compressions, an almost eight-fold reduction in wastednon-compression time, and a fourteen-fold reduction in the time requiredto deliver a first successful breath when performing CPR with theExample System compared to MTMV CPR. All results were found to bestatistically significant, as shown above. Moreover, favorable endpointvariables discussed above only improve the longer CPR is performed.Out-of-hospital CPR is almost always much longer than the example timeused, making the value of the Example System even more pronounced. Forexample, the average total time of no chest compressions is about 21seconds for every minute of CPR in the MTMV CPR group. In starkcontrast, the average total time for no chest compressions using theExample System is only about 8.9 seconds, regardless of how long CPR isperformed.

The Example System was set to deliver fourteen 250 mL breaths perminute, or a Minute Volume of about 3.5 L. Surprisingly, the testingshowed that the Minute Volume for the Example System was an average ofabout 4.06 L per minute; an additional about 506 mL of ventilation. Thisincrease was created by passive ventilation resulting from the effectsof chest compressions on the lung. What is more, this effect was onlyseen during ventilation with the Example System because the I-GEL®suppraglottic airway device maintained the airway and allowed forpassive air movement during chest compressions. This was an unexpectedpositive finding, further supporting the value of aspects of the presentdisclosure.

The foregoing specific embodiments of the present invention as set forthin the specification herein are for illustrative purposes only. Variousdeviations and modifications can be made within the spirit and scope ofthis invention, without departing from the main theme thereof. It willbe appreciated by persons skilled in the art that the present inventionis not limited by what has been particularly shown and described hereinabove.

1. A system for performing simultaneous ventilation and resuscitation ofa patient comprising: an oxygen source; at least one inspiration controlvalve disposed between the oxygen source and the patient; a breathingapparatus disposed downstream from the inspiration control valve, thebreathing apparatus configured to form an air seal with at least aportion of the patient's respiratory tract such that a gas includingoxygen can flow from the oxygen source to the lungs; at least oneexpiration control valve configured to selectively actuate an exhalationvalve; at least one indicator for indicating when chest compressionsshould be performed; and at least one timer for synchronizing actuationof the at least one inspiration control valve, the at least oneexpiration control valve, and the indicator, thereby enabling continuouschest compressions to be provided to the patient while the patientundergoes inspiration and expiration. 2-20. (canceled)